1. Field of the Invention
This invention generally relates to a bicycle front derailleur. More specifically, the present invention relates to a bicycle front derailleur, which is designed to be attached to a seat tube of a bicycle frame and which includes a mounting fixture adjustably coupled to the fixed member to adjust the angular orientation/position of the chain guide relative to the frame.
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle. One component that has been extensively redesigned is the bicycle front derailleur.
Generally, a front derailleur includes a fixed member non-movably secured to the bicycle frame and a movable member movably coupled to the fixed member using a linkage assembly so as to be laterally movable relative to the fixed member. The movable member includes an attachment portion and a chain guide with a pair of cage plates for contacting and moving a chain between the front sprockets. A biasing member normally biases the movable member and chain guide to a retracted position or an extended position relative to the fixed member. The fixed member of the front derailleur of the bicycle is typically mounted onto the bicycle frame adjacent to the front sprockets. Specifically, the front derailleur is usually clamped onto the seat tube of the frame.
The movable member is movable relative to the fixed member by pulling or releasing a shift control cable to move against or due to the biasing force of the biasing member. In particular, the movable member and fixed member usually are interconnected through pivotal links of the linkage assembly, while the control cable is connected to one of the pivotal links. Thus, upon pulling the shift control cable, a torque is applied to the link to move the movable member against the biasing force of the biasing member. Alternatively, when the shift control cable is released, the biasing member applies torque in the opposite direction to cause the movable member to move in the opposite direction. Depending on the arrangement and locations of the cable guides, the cable attachment member of the front derailleur may need to be configured differently for different types of frames.
While these front derailleurs generally work well, because they are clamped onto the seat tube, the position/orientation may not be optimal (i.e., shifting performance may not be optimal). In other words, it can be difficult to clamp these prior front derailleurs at the proper location. Moreover, it is possible for these types of front derailleurs to sometimes move slightly during use, due to a loosened fastener, repeated vibrations and/or contact with an obstruction or the like. Accordingly, some bicycles have been provided with permanent (i.e., welded or brazed-on) derailleur mounting portions that are fixed to the seat tube of the frame at the appropriate location. These permanent derailleur fastening structures generally work well. However, it is possible that during manufacture of bicycle frames with such permanent derailleur mounting portions for some variance in the various bicycle frames on the production line. Moreover, derailleurs can have different configurations among various models/brands. Accordingly, even when a permanent (i.e., welded or brazed-on) derailleur mounting portion fixed to the seat tube is utilized, the position/orientation may not be optimal (i.e., shifting performance may not be optimal).
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved bicycle front derailleur. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.